1 Titel van de presentatie Rein Boshuisen, PME Analysis and Performance of a lightweight over-actuated 450mm wafer chuck R. Boshuisen, PME 09-06-2010

1Titel van de presentatie

Rein Boshuisen, PME

Analysis and Performance of a lightweight over-actuated 450mm wafer chuck

R. Boshuisen, PME09-06-2010


Contents

• Introduction

• Problem Description

• Principle of Over-actuation

• Test Setup and Analysis

• Improvements on the Current Setup

• Conclusions

Over-actuation of a wafer chuck


Problem description

Typically wafer chucks are actuated as rigid bodies. Larger wafers leads to heavier wafer stages:

200 mm Wafer

m kg

300 mm Wafer

> 3 x m kg

450 mm Wafer

> 11 x m kg

Z

Y

X

Width: 1.5

Depth 1.5

Thickn: 1.5

Width: 1.5

Depth 1.5

Thickn: 1.5

Modal analysisModal analysisOver-actuation of a wafer chuck


Drawbacks of large wafers and chucks:• Larger actuation forces and deformation• Larger power dissipation and thermal load • Internal modes still critical to performance

Z

Y

X

Problem description

Desire to have a LARGE chuck with LOW Mass and HIGH internal modes

Modal analysisModal analysisOver-actuation of a wafer chuck


zF

z

ALTERNATIVE means of ACTUATOR placement

Actuation in nodes

zFzFSymmetrical actuation

zF zF zF

Challenge deal with infinitely many modes, without adding as many actuators and control complexity

Alternative: Over-Actuation


6Titel van de presentatieModal analysisModal analysis

Eigenmodes of a chuck


7Titel van de presentatieOver-actuation of a wafer chuck

First eigenmode - Example

8Titel van de presentatieModal analysisModal analysis




• Actuators on nodeline?

• Change nodelines?

Modal analysisModal analysis




1Langelaar TU Delft

y

x

Topology optimization1 of chuck



5

1

25

1

25

1

2min

f RyTff Rx

Tff z

Tf BBB

Z Rx Ry

00

01

0

001

2

2

kms

ms

Mechanics

T CB

Modal Coordinates

Physical Coordinates

Minimize the contribution by varying actuator position and cavity diameter :

a d

Optimization Strategy


12Titel van de presentatieModal analysisModal analysisOver-actuation of a wafer chuck

Optimization result I


184 Hz 270 Hz 270 Hz

349 Hz 521 Hz

Actuator location

Green zero displacement




Optimization result II


Optimization result II


Wafer chuck demonstrator motions in Z, Rx, and Ry

Z

Y

X

Three linear encoders

Folded Flexures (3x),

Fixing Rz, X and Y Actuator assembly (5x)

Frame

Modal analysisModal analysis

Realized Test Setup



Conventional actuation around COG

Over-actuation around COG

Realized Test Setup



Measured Result I


Measured Result II


Control of the chuck

ChuckDynamics

Loc ->CoGActuation matrix

3 PID controllers

3 Sensors

Z

RX

RY

Control with standard industrial controller Bosch-RexRoth NYCe 4000



Performance of the setup

Conventional Over-ActuatedBandwidths:

ZRXRY

50 Hz60 Hz50 Hz

102 Hz100 Hz100 Hz

Standstill Performance RMS

ZRXRY

30 nm 150 nrad135 nrad

7 nm35 nrad30 nrad

Factor 2 in bandwidth, 4 in stiffness

Factor 5 improvement

Over-Actuation shows clear benefits compared to conventional actuation!



Why still excitation of the modes??


• Improved model

• No Symmetry – Possible causes• Actuator 5• Gravity Compensators• Plate springs• Chuck

The analysis only partially explains the mode excitations


Mode excitation analysis


• Sensor-placement / Over-Sensing


Improvements of the current setup


Control of the chuck

ChuckDynamics

Loc ->CoGActuation matrix

3 PID controllers

3 Sensors

Z

RX

RY

Control with: Matlab/Simulink, using xPc Target software



Adjust Sensorposition such, that the excitation of the modes is not converted to CoG movement

• Place sensor in a node

• Symmetric sensor placement


Over-Sensing


Over-Sensing


• This sensor placement can distinguish the first and second eigenmode from the rigid body movement

• Active damping of first eigenmode!


Over-Sensing


Conventional Over-Actuated + first mode active damping

Bandwidths:ZRXRY

100 Hz100 Hz100 Hz

200 Hz150 Hz150 Hz

Standstill Performance RMS

Sensor 1Sensor 2Sensor 3Sensor 4

4.0 nm5.8 nm4.6 nm4.6 nm

1.8 nm1.9 nm1.9 nm1.9 nm


Over-Sensing - Performance


• Over-actuation is succesfully implemented on a wafer chuck with an increased performance as result.

• Symmetry is critical for the positions of the nodelines on the diagonals

• Include sensor position optimization in the design phase

• Use four sensors to be able to actively damp the first eigenmode


Conclusion


Rein Boshuisen, PME

Analysis and Performance of a lightweight over-actuated 450mm wafer chuck

R. Boshuisen, PME09-06-2010



Dynamic Analysis – effect of rotated chuck



Dynamic Analysis – effect of Gravity Compensator



Damping

• Chuck is very lightly damped, increasing damping, reduces maximum peak-hight, leading to less sensitivity of the actuator placement


Documents

1 Titel van de presentatie Rein Boshuisen, PME Analysis and Performance of a lightweight over-actuated 450mm wafer chuck R. Boshuisen, PME 09-06-2010